Various sensors for collecting information, for example, medical information in the human body have been developed and used. In addition to a technique for collecting information in the human body, a technique for transmitting the collected information to the outside of the human body is important.
A communication cable method is one of general data transmitting methods. A communication cable method is applied to, for example, an endoscope which is developed for observing the stomach and the intestines. In the communication cable method, a cable made of a conducting wire or an optic fiber is inserted into the human body through a throat of a patient. While the communication cable method has high reliability and high data quality, it may cause severe pain to the patient.
In order to solve the above-mentioned problem, Given Imaging LTD. in Israel has developed a capsule type endoscope called M2A. When a patient swallows the capsule type endoscope in a form of a tablet, video data in the human body photographed by a camera of the endoscope are transmitted to an external-receiving unit, and displayed in a monitor.
However, in the capsule type endoscope, since a radio wave is used to transmit a signal, power consumption is large, an operation time is short, and the receiving sensitivity is deteriorated due to interference of various electric waves from the outside of the human body. In addition, radio-transmitting apparatus such as a converter circuit for converting a video signal into a high frequency signal and an antenna for signal transmission, etc. may be required. Accordingly, the volume and production cost may be increased. Also, the high frequency may be harmful to the human body.